P1780 Fault Code in Ford: Causes, Symptoms, and Fixes

The PNP / TR switch tells the TCM & ECM which gear (P, R, N, D, etc.) the transmission selector is in. If the signal is missing, out of range, or inconsistent, the ECU sets code P1780.

Symptoms

1. Check Engine Light ON
2. Transmission may not shift properly
3. Vehicle may start only in certain gears or not at all
4. Harsh engagement when shifting out of Park/Neutral
5. Possible limp mode activation

Common Causes

1. Faulty PNP (Park/Neutral Position) switch / Transmission Range Sensor
2. Misadjusted shift cable or linkage
3. Damaged wiring or loose/corroded connectors
4. Contaminated or low transmission fluid (affecting sensor area)
5. Faulty TCM / ECM (rare)

Diagnosis Steps

1. Check shift lever operation – ensure linkage is properly aligned
2. Inspect wiring & connectors – look for loose, corroded, or broken wires at the range switch
3. Test the PNP / TR switch – continuity/resistance check with multimeter while moving the shifter through all positions
4. Scan tool check – verify if TCM is receiving the correct gear position input
5. Check fluid condition (if switch is mounted internally)

Possible Repairs

1. Adjust or replace PNP / TR switch
2. Repair / replace damaged wiring or connectors
3. Adjust shift cable/linkage
4. Replace contaminated transmission fluid (if affecting sensor)
5. Reprogram / replace TCM / ECM if needed